Clean up test databases at exit

Sources/SQLiteData/CloudKit/DefaultSyncEngine.swift

@@ -55,11 +55,7 @@
     }
 
     public static var testValue: SyncEngine {
-      try! SyncEngine(
-        for: DatabasePool(
-          path: URL.temporaryDirectory.appending(path: "\(UUID().uuidString).sqlite").path()
-        )
-      )
+      try! SyncEngine(for: temporaryDatabasePool())
     }
   }
 #endif

Sources/SQLiteData/Internal/TemporaryDatabase.swift

@@ -0,0 +1,36 @@
+import Foundation
+import GRDB
+
+func temporaryDatabasePool(configuration: Configuration = Configuration()) throws -> DatabasePool {
+  try FileManager.default.createDirectory(
+    at: temporaryDatabaseDirectory, withIntermediateDirectories: true
+  )
+  return try DatabasePool(
+    path: temporaryDatabaseDirectory
+      .appending(path: "\(UUID().uuidString).db")
+      .path(percentEncoded: false),
+    configuration: configuration
+  )
+}
+
+private let temporaryDatabaseDirectory: URL = {
+  let directory = URL.temporaryDirectory.appending(
+    path: "co.pointfree.SQLiteData",
+    directoryHint: .isDirectory
+  )
+  let processDirectories =
+    (try? FileManager.default.contentsOfDirectory(at: directory, includingPropertiesForKeys: nil))
+    ?? []
+  for processDirectory in processDirectories {
+    guard
+      let processIdentifier = pid_t(processDirectory.lastPathComponent),
+      kill(processIdentifier, 0) != 0,
+      errno == ESRCH
+    else { continue }
+    try? FileManager.default.removeItem(at: processDirectory)
+  }
+  return directory.appending(
+    path: "\(ProcessInfo.processInfo.processIdentifier)",
+    directoryHint: .isDirectory
+  )
+}()

Sources/SQLiteData/StructuredQueries+GRDB/DefaultDatabase.swift

@@ -36,10 +36,7 @@ public func defaultDatabase(
     }
     database = try DatabasePool(path: path ?? defaultPath, configuration: configuration)
   case .preview, .test:
-    database = try DatabasePool(
-      path: "\(NSTemporaryDirectory())\(UUID().uuidString).db",
-      configuration: configuration
-    )
+    database = try temporaryDatabasePool(configuration: configuration)
   }
   return database
 }